TEM4: Proteins and Enzymes

TEM4 (Tumor endothelial marker 4) is a Rho-specific GEF (guanine-nucleotide exchange factor) with novel structural and regulatory properties and predominant expression in the heart. Rho GTPases, which are activated by specific GEFs, play pivotal roles in several cellular functions. TEM4, encoding a protein containing 1510 amino acids, contains a RhoGEF-specific Dbl homology (DH) domain but lacks their typical pleckstrin homology domain. TEM4 couples tyrosine kinase signals with the activation of the rho/rac GTPases, thus leading to cell differentiation and/or proliferation. Elevated levels of TEM4, TEM5, TEM6, TEM7 and TEM7R were also raised in breast cancer tissues. TEM4 could also prove to be useful as a target, therapeutically.